Contactless trigger with rotational magnetic sensor for a power tool

ABSTRACT

A trigger assembly for a power tool includes a housing, a moveable plunger extending from a surface of the housing, the movable plunger includes a first end disposed externally from the housing and a second end disposed internally within the housing. The trigger assembly further includes a trigger shoe coupled to the first end of the moveable plunger, and an arm including a first side that is moveably connected to the second end of the moveably plunger and a second side that is coupled to a magnet. The trigger assembly also includes a sensor configured to sense a magnetic field of the magnet. Movement of the trigger shoe rotates the magnet, and alters the magnetic field sensed by the sensor.

RELATED APPLICATIONS

This application claims the benefit of U.S. patent application Ser. No.17/056,090, filed Nov. 17, 2020, which is a national phase filing under35 U.S.C. § 371 of International Application No. PCT/US2020/032442,filed May 12, 2020, which claims the benefit of U.S. Provisional PatentApplication No. 62/847,103, filed May 13, 2019, and U.S. ProvisionalPatent Application No. 62/870,353, filed Jul. 3, 2019, the entirecontent of each of which is hereby incorporated by reference.

FIELD

Embodiments described herein relate to a trigger or other user input forelectronic power tools.

SUMMARY

Input devices, such as a trigger on a power tool, may be physicallycoupled to one or more electronic components, such as variableresistors, relays, and the like. Physical connections on input devices,including triggers, may wear over time, thereby reducing the operationallife of the tool. Thus, it would be advantageous to utilize contactlesssensing device to reduce wear and increase life of the input devicesand/or the power tool.

In one embodiment, a trigger assembly for a power tool includes ahousing, a moveable plunger extending from a surface of the housing, themovable plunger includes a first end disposed externally from thehousing and a second end disposed internally within the housing. Thetrigger assembly further includes a trigger shoe coupled to the firstend of the moveable plunger, and an arm including a first side that ismoveably connected to the second end of the moveably plunger and asecond side that is coupled to a magnet. The trigger assembly alsoincludes a sensor configured to sense a magnetic field of the magnet.Movement of the trigger shoe rotates the magnet, and alters the magneticfield sensed by the sensor.

The sensor of the above trigger assembly may be configured to be inelectronically coupled to a controller of the power tool, and thecontroller may be configured to control an output of the power tool.

The sensor of the above trigger assembly may also be configured tooutput a signal to the controller based on the sensed magnetic field.

The output of the sensor in the above trigger assembly may be a voltageindicative of a position of the trigger shoe.

The above trigger assembly, wherein the magnet may be an annular magnetconfigured to rotate based on movement of the arm.

The above trigger assembly, wherein the sensor may be configured tosense a change in the magnetic field of the annular magnet in responseto the annular magnet rotating.

The above trigger assembly may further include a selector disposed on asurface of the housing. The trigger assembly may further include a pinincluding a first end that is engageable with the selector and a secondend that is coupled to the selector magnet, and a selector sensorconfigured to sense a magnetic field of the selector magnet. The axialmotion of the selector may be configured to rotate the selector magnet,thereby altering the magnetic field sensed by the sensor.

The above trigger assembly, wherein the selector sensor may beconfigured to sense a polarity of the selector magnet, and output adigital signal to the controller based on the sensed polarity.

The above trigger assembly, wherein the controller may be configured toexecute an operating mode selected from a number of operating modes ofthe power tool based on the digital signal received from the selectorsensor.

The above trigger assembly, wherein operating modes of the power toolmay include a forward operating mode and a reverse operating mode.

In an additional embodiment, a method for controlling an output of anelectric power tool is described, according to some embodiments. Themethod includes actuating a trigger shoe of the electric power tool in afirst linear direction, wherein the actuation of the trigger shoe movesa movable plunger in the first linear direction. The method furtherincludes converting the linear movement of the movable plunger into arotation movement of a movable arm in a first rotational direction, androtating an annular magnet coupled to the movable arm in the firstrotational direction. The method also includes sensing a parameter of amagnetic field generated by the annular magnet at a first magneticsensor and converting the parameter of the rotating magnetic field to anoutput voltage. The method also includes receiving, at a controller ofthe electric power tool, the output voltage, and controlling the outputof the electric power tool based on the received output voltage.

The above method may also include the output of the electric power toolbeing a rotational speed.

The above method may also include the sensed parameter being a magneticflux density vector component.

The above method may also include the first magnetic sensor being ananalog rotational magnetic field sensor.

The above method may also include sensing a parameter of the magneticfield generated by the annular magnet at a second magnetic sensor,wherein the second magnetic sensor is a digital magnetic sensor.

The above method may also include initiating a wake-up process for thecontroller based on the controller receiving an output of the secondmagnetic sensor.

In another embodiment, a power tool is described. The power toolincludes a trigger assembly. The trigger assembly includes a triggershoe configured to be actuated in a first linear direction, wherein theactuation of the trigger shoe moves a movable plunger in the firstlinear direction. The trigger assembly further includes a movable armconfigured to convert the linear movement of the movable plunger into arotational movement of a movable arm in a first rotational direction,the movable arm further configured to rotate an annular magnet coupledto the movable arm in the first rotational direction. The triggerassembly also includes a magnetic sensor configured to sense a firstparameter of a magnetic field generated by the annular magnet, whereinthe magnetic sensor is configured to convert the magnetic field to anoutput voltage representative of a position of the trigger shoe. Thepower tool also includes a controller configured to receive the outputvoltage from the magnetic sensor and control the output of the powertool based on the received output voltage.

The above described power tool, wherein the output of the power tool maybe a rotational speed.

The above described power tool may also include a second magnetic sensorconfigured to sense a second parameter of the annular magnet andtransmit an output of the controller, wherein the second magnetic sensoris a digital magnetic sensor, and the second parameter is a polarity ofthe annular magnet.

The above described power tool, wherein the controller is furtherconfigured to initiate a wake-up process for the controller based on thecontroller receiving the output of the second magnetic sensor.

Before any embodiments are explained in detail, it is to be understoodthat the embodiments are not limited in its application to the detailsof the configuration and arrangement of components set forth in thefollowing description or illustrated in the accompanying drawings. Theembodiments are capable of being practiced or of being carried out invarious ways. Also, it is to be understood that the phraseology andterminology used herein are for the purpose of description and shouldnot be regarded as limiting. The use of “including,” “comprising,” or“having” and variations thereof are meant to encompass the items listedthereafter and equivalents thereof as well as additional items. Unlessspecified or limited otherwise, the terms “mounted,” “connected,”“supported,” and “coupled” and variations thereof are used broadly andencompass both direct and indirect mountings, connections, supports, andcouplings.

In addition, it should be understood that embodiments may includehardware, software, and electronic components or modules that, forpurposes of discussion, may be illustrated and described as if themajority of the components were implemented solely in hardware. However,one of ordinary skill in the art, and based on a reading of thisdetailed description, would recognize that, in at least one embodiment,the electronic-based aspects may be implemented in software (e.g.,stored on non-transitory computer-readable medium) executable by one ormore processing units, such as a microprocessor and/or applicationspecific integrated circuits (“ASICs”). As such, it should be noted thata plurality of hardware and software based devices, as well as aplurality of different structural components, may be utilized toimplement the embodiments. For example, “servers,” “computing devices,”“controllers,” “processors,” etc., described in the specification caninclude one or more processing units, one or more computer-readablemedium modules, one or more input/output interfaces, and variousconnections (e.g., a system bus) connecting the components.

Relative terminology, such as, for example, “about,” “approximately,”“substantially,” etc., used in connection with a quantity or conditionwould be understood by those of ordinary skill to be inclusive of thestated value and has the meaning dictated by the context (e.g., the termincludes at least the degree of error associated with the measurementaccuracy, tolerances [e.g., manufacturing, assembly, use, etc.]associated with the particular value, etc.). Such terminology shouldalso be considered as disclosing the range defined by the absolutevalues of the two endpoints. For example, the expression “from about 2to about 4” also discloses the range “from 2 to 4”. The relativeterminology may refer to plus or minus a percentage (e.g., 1%, 5%, 10%,or more) of an indicated value.

It should be understood that although certain drawings illustratehardware and software located within particular devices, thesedepictions are for illustrative purposes only. Functionality describedherein as being performed by one component may be performed by multiplecomponents in a distributed manner. Likewise, functionality performed bymultiple components may be consolidated and performed by a singlecomponent. In some embodiments, the illustrated components may becombined or divided into separate software, firmware and/or hardware.For example, instead of being located within and performed by a singleelectronic processor, logic and processing may be distributed amongmultiple electronic processors. Regardless of how they are combined ordivided, hardware and software components may be located on the samecomputing device or may be distributed among different computing devicesconnected by one or more networks or other suitable communication links.Similarly, a component described as performing particular functionalitymay also perform additional functionality not described herein. Forexample, a device or structure that is “configured” in a certain way isconfigured in at least that way but may also be configured in ways thatare not explicitly listed.

Other aspects of the embodiments will become apparent by considerationof the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a power tool including a contactlesstrigger, according to some embodiments.

FIG. 2 is a perspective view of the power tool of FIG. 1 with a portionof a housing removed to show the contactless trigger, according to someembodiments.

FIG. 3 is a perspective view of the contactless trigger of FIG. 2 ,according to some embodiments.

FIG. 4 is an exploded perspective view of the contactless trigger ofFIG. 3 , according to some embodiments.

FIG. 5 is a perspective sectional view of the contactless trigger ofFIG. 3 with a portion of a housing removed, according to someembodiments.

FIG. 6A is a side view of the contactless trigger of FIG. 3 with aportion of a housing removed in a non-depressed position, according tosome embodiments.

FIG. 6B is a side view of the contactless trigger of FIG. 3 with aportion of a housing removed in a depressed position, according to someembodiments.

FIG. 7 is an alternate exploded perspective view of the contactlesstrigger of FIG. 3 , according to some embodiments.

FIG. 8 is a side sectional view of the contactless trigger of FIG. 3 ,according to some embodiments.

FIG. 9 is a top sectional view of the contactless trigger of FIG. 3 ,according to some embodiments.

FIG. 10A is a perspective sectional view of the contactless trigger ofFIG. 3 with a portion of a housing removed, according to someembodiments.

FIG. 10B is a perspective view of a ball detent of the contactlesstrigger of FIG. 3 , according to some embodiments.

FIG. 11 is a functional diagram illustrating the interface between amagnet and multiple magnetic sensors with an input device in a firstposition, according to some embodiments.

FIG. 12 is a functional diagram illustrating the interface between themagnet and magnetic sensors of FIG. 11 with an input device in a secondposition, according to some embodiments.

FIG. 13 is a graph illustrating an output of an analog magnetic sensorversus an amount of trigger travel, according to some embodiments.

FIG. 14A is a graph illustrating an output of a digital magnetic sensorversus an amount of trigger travel, according to some embodiments.

FIG. 14B is a graph illustrating an output of a dual output digitalmagnetic sensor versus an amount of travel of a selector device,according to some embodiments.

FIG. 15 is a block diagram of a brushless power tool, according to someembodiments.

FIG. 16 is a circuit diagram of the power switching network described inFIG. 15 , according to some embodiments.

FIG. 17 is a flow chart illustrating a process for controlling theoutput of an electric power tool, according to some embodiments.

FIG. 18 is a graph illustrating a motor drive profile of an electrictool, according to some embodiments.

FIGS. 19A, 19B, and 19C are top views of an alternative contactlesstrigger assembly, according to some embodiments.

FIGS. 20A, 20B, and 20C are top views of an alternate configuration ofthe contactless trigger assembly of FIGS. 19A-19C, according to someembodiments.

DETAILED DESCRIPTION

FIG. 1 illustrates an example power tool 100, according to oneembodiment. The power tool includes a housing 105, a battery packinterface 110, a driver 115 (e.g., a chuck or bit holder), and acontactless trigger assembly 200. The power tool 100 may further have amode selection device. For example, the mode selection device may be aforward-reverse selector 204, which can allow a user to control thedirection of a rotating portion of the tool. While FIG. 1 shows aspecific power tool with a rotational output, it is contemplated thatthe herein described contactless trigger designs may be used withmultiple types of power tools, such as drills, drivers, impact drivers,impulse drivers, saws (e.g. band saws, circular saws, miter saws, andthe like), lights, hammer drills, nail guns, staple guns, liquiddispenser (e.g. caulk guns), crimping and/or clamping devices, oranother type of power tool that uses a brushless DC motor that iscontrolled via a user input (e.g. a trigger).

FIG. 2 illustrates a cross-sectioned view of the power tool 100,according to some embodiments. The contactless trigger assembly 200(also referred as the trigger 200) and the forward-reverse selector 204(also referred to as the selector 204) are types of user inputs to acontroller associated with the tool 100, as will be described below. Forexample, the trigger 200 may produce an analog signal indicative of adesired speed or torque that varies based on the travel distance of atrigger shoe 228. For example, an analog magnetic sensor may be incommunication with a magnet within the contactless trigger assembly 200.The forward-reverse selector 204, which may be considered part of thecontactless trigger assembly, may be able to be moved from a firstdiscrete position to a second discrete position. Similar to above, theforward-reverse selector 204 may include a magnet that is incommunication with a magnetic sensor, such as a digital magnetic sensor,thereby outputting a signal to a controller of the tool 100 based on theposition of the forward-reverse selector 204. An example of such acontroller is described further below (see motor controller 930 in FIG.15 ).

FIGS. 3 and 4 illustrate a detailed view of the contactless triggerassembly 200, according to some embodiments. The contactless triggerassembly 200 includes a housing 208 with a first housing section 212 anda second housing section 216 that are removably couplable to oneanother. The first housing section 212 includes rails 220 extending froma first surface 224 of the housing 208. The first surface 224 of thehousing 208 is defined by both the first housing section 212 and thesecond housing section 216 when the first and second housing sections212, 216 are coupled. The rails 220 are positioned to allow the triggershoe 228 to slide along a length of the rails 220, such that the traveldistance of the trigger shoe 228 may be actualized. The first surface224 of the housing 208 further includes a moveable plunger 232 extendingtherefrom. The moveable plunger 232 includes a first end 236 that issized to be received by a circular recessed portion 240 of the triggershoe 228, such that the trigger shoe 228 and the moveable plunger 232are coupled, providing in sync movement between the trigger shoe 228 andthe moveable plunger 232. The diameter of the circular recessed portion240 is not significantly larger than the diameter of the moveableplunger 232, allowing a tight fitting between the moveable plunger 232and the trigger shoe 228. In alternate embodiments, the moveable plunger232 and the trigger shoe 228 may be coupled via alternate means such asfasteners, adhesive, or the like. In some examples, the housing 208 maybe omitted, and the above components may be installed directly withinthe housing 105 of the tool 100.

A second end 244 of the moveable plunger 232, opposite the first end 236of the moveable plunger 232, is disposed in an internal portion 238 ofthe housing 208. The first surface 224 includes a hole 248, with anopening member 252 disposed in the hole 248. The moveable plunger 232 isdisposed in the opening member 252 such that the moveable plunger 232slides on an annular surface 254 of the opening member 252, with thefirst end 236 of the moveable plunger 232 being disposed externally ofthe housing 208 and the second end 244 of the moveable plunger 232 beingdisposed internally of the housing 208. The second end 244 of themoveable plunger 232 includes a recessed portion 256 (see FIG. 5 ) sizedto receive a stationary rod 260 that is coupled to an internal surface264 of the housing 208 that is opposite that of the first surface 224 ofthe housing 208. As shown in FIG. 5 , the recessed portion 256 of themoveable plunger 232 includes a length that is sized to allow themoveable plunger 232 to move the travel distance, such that the triggershoe 228 moves the travel distance.

With reference to FIGS. 4 and 5 , a spring 268 is disposed on thestationary rod 260 and an external surface of the second end 244 of themoveable plunger 232, with the spring 268 being disposed between a plate272 of the stationary rod 260 and a cam 276 of the moveable plunger 232.The plate 272 of the stationary rod 260 is directly coupled to theinternal surface 264 of the housing 208. The cam 276 of the moveableplunger 232 includes a diameter that is larger than the diameter of thespring 268, such that the spring 268 biases a first surface 280 of thecam 276. The cam 276 prevents the second end 244 of the moveable plunger232 from exiting the internal portion 238 of the housing 208 due to thecam 276 having a larger diameter than that of the opening member 252.The spring 268 biases the first surface 280 of the moveable plunger 232along an axis A, such that a second surface of the moveable plunger 232interfaces with the opening member 252.

As illustrated in FIG. 5 , the internal portion 238 of the housing 208further includes an annular magnet 284 coupled to the cam 276 of themoveable plunger 232 via an arm 288. The arm 288 is moveably coupled tothe cam 276 via a first pin 292 of the arm 288. The arm 288 is alsopermanently coupled to the annular magnet 284 via a projection 293.Accordingly, as the moveable plunger 232 moves along the axis A, the arm288 is rotated about an axis B, which intersects the center of theannular magnet 284, in a direction C. As the arm 288 rotates in thedirection C, the annular magnet 284 also rotates in the direction C.Rotation of the annular magnet 284 alters the magnetic field detected byan analog magnetic sensor on a printed circuit board (PCB) 418 (seeFIGS. 6A and 6B). In some embodiments, the analog magnetic sensor is ananalog rotational magnetic field sensor. The analog rotational magneticfield sensor may be configured to output a linear voltage to acontroller of the tool 100 (see, e.g., motor controller 930 of FIG. 15). The linear voltage may be indicative of a position of the triggershoe 228, and may be used to control an associated parameter of the tool100, such as the rotational speed of a motor. In other embodiments, theannular magnet 284 may also be in communication with a digital magneticsensor. The digital magnetic sensor may be configured to transition froma first state to a second state based on detecting a change of themagnetic field produced by the annular magnet 284 in response torotating as the trigger shoe 228 is depressed.

In other embodiments, the digital magnetic sensor outputs a first valuewhen the rotation magnet produces a magnetic field indicative of themagnet being in a first predefined position (e.g. associated with afully released trigger shoe 228). The rotational magnetic sensor maythen be configured to provide a second value when the magnet transitionsaway from the first predefined position. The transitional output of thedigital magnetic sensor may provide an input to a controller of the tool100 (see, e.g., motor controller 930 of FIG. 15 ), which indicates thatthe controller should turn on (e.g., a wake-up signal). In still furtherembodiments, the annular magnet 284 may be in communication with only adigital magnetic sensor. For example, in some embodiments, where thetool 100 operates at a single speed or includes a separate speedadjusting mechanism (e.g., a speed dial), only a digital magnetic sensoris included to detect the annular magnet 284.

Turning to FIG. 6A, when the trigger shoe 228 is in a relaxed state, thespring 268 biases the moveable plunger 232 and, thus, the trigger shoe228, to an extended position relative to the first surface 224 of thehousing 208. At this time, the annular magnet 284 is in a firstposition, with a first magnetic field relative to the PCB 418, which theanalog rotational magnetic field sensor detects. The first magneticfield detected by the analog rotational magnetic field sensor is thenconverted to a first output value, which is then received by acontroller of the tool 100.

Turning to FIG. 6B, when the trigger shoe 228 is depressed, the triggershoe 228 moves the moveable plunger 232 along the axis A, such that thetrigger shoe 228 moves toward the first surface 224 of the housing 208.Movement of the moveable plunger 232 biases the spring 268 toward theplate 272 of the stationary rod 260, thereby, also moving the cam 276toward the plate 272. This, in turn, causes the arm 288 to pivot aboutthe axis B, rotating the annular magnet 284 about the axis B in thedirection C. At this time, the annular magnet 284 is in a secondposition, with a second magnetic field relative to the PCB 418, whichthe analog rotational magnetic field sensor detects. The second magneticfield detected by the analog rotational magnetic field sensor is thenconverted to a second output voltage that is distinct from the firstoutput voltage, which is then received by the controller of the tool100.

With reference to FIG. 6A, when the force depressing the trigger shoe228 is removed, the spring 268 biases the cam 276, which moves themoveable plunger 232 and, thus, the trigger shoe 228, along the axis Ain a direction away from the first surface 224 of the housing 208.Movement of the cam 276 causes the arm 288 to pivot about the axis B ina direction opposite to that of the direction C. The annular magnet 284is therefore rotated in the opposite direction to that of the directionC until movement of the cam 276 is inhibited by the opening member 252.At this time, the annular magnet 284 is in the first position, with thefirst magnetic field, which the analog rotational magnetic field sensordetects. The first magnetic field detected by the analog rotationalmagnetic field sensor is then converted to the first output voltage,which is then received by the controller of the tool 100.

As illustrated in FIGS. 7-8 , the contactless trigger 200 includes theforward-reverse selector 204, as described above. A camming assembly 300communicates with recessed portion walls 304 of the selector 204 via aselector arm 308 (see also FIG. 6 ) that has a portion extending throughan opening 312 (see also FIG. 4 ) of the housing 208. The opening 312 isdefined by both the first housing section 212 and the second housingsection 216, on a second surface 314 of the housing 208 that isperpendicular to the first surface 224 of the housing 208.

With reference to FIG. 8 , the selector arm 308 includes a center pinportion 316, an intermediate portion 320, and an upwardly extendingportion 324. The center pin portion 316 extends through the opening 312of the housing 208, such that the center pin portion 316 is positionedboth in the internal portion 238 of the housing 208 and externally fromthe housing 208. An end of the center pin portion 316 that is in theinternal portion 238 of the housing 208 is coupled to a magnet 328. Theintermediate portion 320 is disposed externally of the housing 208 andis integrally connected to the center pin portion 316. The intermediateportion 320 extends away from the opening 312 of the housing 208, alongthe second surface 314. The upwardly extending portion 324 is integrallyconnected to the intermediate portion 320 and is perpendicular to theintermediate portion 320, such that the upwardly extending portion 324extends away from the second surface 314. The upwardly extending portion324 includes a first side 332 and a second side 336 opposite the firstside 332, the first side 332 and the second side 336 are curved (shownin FIG. 9 ).

A ball detent 340 is disposed in a recess in the internal portion 238 ofthe housing 208. The ball detent 340 is biased toward an outside surfaceof the end of the center pin portion 316 via a ball detent spring 344(see FIG. 7 ). The outside surface of the center pin portion 316includes a first recession 348, a second recession 350, and a thirdrecession 352, each sized to receive the ball detent 340.

With reference to FIGS. 9-10B, the selector 204 may move along an axis Din a first direction and a second direction, the second direction beingopposite from the first direction. When the selector 204 moves along theaxis D in the first direction, a first wall 356 of the recessed portionwalls 304 of the selector 204 comes into contact with the first side 332of the upwardly extending portion 324. Since the first side 332 iscurved, as the first wall 356 biases the first side 332, the upwardlyextending portion 324 rotates the intermediate portion 320 and, thus,the center pin portion 316, about an axis E (see FIGS. 8, 10A), whichextends through the center of the center pin portion 316, in a directionF (see FIG. 9 ). At this time, the ball detent 340 is moved out of thesecond recession 350, which acts as a neutral positon, and along theoutside surface of the center pin portion 340. As the first wall 356continues to bias the first side 332, the center pin portion 316continues to rotate. Continued rotation of the center pin portion 316and, thus, the magnet 328, is inhibited by the ball detent 340 beingreceived in the first recession 348, such that the center pin portion316 is locked in a first position (shown in FIG. 10B).

When the selector 204 moves along the axis D in the second direction, asecond wall 360 of the recessed portion walls 304 of the selector 204comes into contact with the second side 336 of the upwardly extendingportion 324. Since the second side 336 is curved, as the second wall 360biases the second side 336, the upwardly extending portion 324 rotatesthe intermediate portion 320 and, thus, the center pin portion 316,about the axis E in a direction opposite to that of the direction F. Asthe second wall 360 continues to bias the second side 336, the centerpin portion 316 continues to rotate. Continued rotation of the centerpin portion 316 and, thus, the magnet 328, is inhibited by the balldetent 340 being received in the second recession 350, such that thecenter pin portion 316 is locked in the neutral position (shown in FIG.10B). Continued force imparted by the second wall 360, moves the balldetent 340 out of the second recession 350, along the surface of thecenter pin portion 340, and into the third recession 352, where thecenter pin portion 316 is locked in a second position.

As the camming assembly 300 rotates between the first position and thesecond positon, the magnetic field of the magnet 328 varies relative tostationary elements of the assembly, such as the PCB 418. This variationof the magnetic field is detected by a magnetic field sensor 420 locatedon the PCB 418. In one embodiment, the magnetic field sensor 420 is adigital magnetic field sensor configured to transition from a firstdigital level to a second digital level based on the digital magneticfield sensor detecting a change in the magnetic polarity of the magnet328. The change in polarity is caused by the rotation of the magnet 328and its associated poles.

In one example, the PCB 418 may extend out of a housing 208 of thecontactless trigger assembly 200. This configuration can allow the PCB418 to extend into the tool 100, thereby providing additional PCB space.For example, as illustrated in FIGS. 3 and 8 , a portion of the PCB 418extends downward out of the housing 208.

FIGS. 11-12 are a functional diagram illustrating the annular magnet 508in communication with an analog magnet sensor 600 and a digital magneticsensor 602, according to some embodiments. In some embodiments, theanalog magnet sensor 600 and the digital magnetic sensor 602 are bothmounted on the PCB 418, described above. In FIG. 11 , the annular magnet508 is in a position associated with the trigger shoe 228 being in afully released position. As shown, the analog magnetic sensor 600 isdetecting a magnetic field generated by the annular magnet. As shown inFIG. 11 , the magnetic field is a result of the magnet flux received bythe analog sensor based on the analog sensor 600 being located at anangle of Θ_(A) from a centerline axis 604 of the annular magnet 508. Thedigital magnetic sensor 602 detects a magnetic field based on thedigital sensor 602 being located at an angle of Θ_(B) from thecenterline axis 604. The digital magnetic sensor 602 may be anomni-directional Hall effect sensor with a normally high state that goeslow as the magnet transitions to a different polarity, thereby makingthe digital sensor 602 insensitive to strong external fields. Theannular magnet 508 is shown to have two poles (for example, a north poleand a south pole). As shown in FIG. 11 , the boundary between the twopoles bisects the diameter of the magnet. A similar magnet design isused in regards to the forward/reverse selector 204.

FIG. 12 shows the annular magnet being in a position associated with thetrigger shoe 228 being in a fully pulled positon. The annular magnet isnow positioned such that the south pole of the magnet is positioned inproximity to the analog magnetic sensor 600, such that the analogmagnetic sensor 600 receiving a magnetic field based on the analogsensor being located at an angle of Θ_(A) to the centerline 604.Accordingly, the annular magnet is now positioned such that the northpole of the magnet is positioned in proximity to the digital magneticsensor 602, and is receiving a magnetic field based on the digitalsensor 602 being located at an angle of Θ_(B) to the centerline 604.Both the analog sensor 600 and the digital sensor 602 may be rotationalHall effect magnetic sensors that are configured to measure a magneticflux density vector component that enters the face of the sensor, andoutputs either a linear proportional signal, or a digital signal. Thus,the magnetic sensors 600, 602 are not being used to measure a flux basedon a distance to a magnetic element. Rather, the magnetic sensors 600,602 measure an angle of the respective sensor to the magnet based on areceived magnetic flux density vector component, thereby allowing thedistance between the sensors 600, 602 and the magnet to remain constantduring operation.

FIG. 13 is a graph showing an example output of an analog magneticsensor, such as magnetic sensor 600, in relation to travel distance ofthe trigger shoe 228. As shown in FIG. 13 , the output of the analogsensor increases in a generally linear fashion as the trigger shoe 228moves from an initial relaxed position (depressed 0 mm) to a fullydepressed position (depressed 8 mm), as shown by output trend line 700.The particular voltage levels and travel distances are merely examples,as different levels and distances are used in other embodiments.Further, in some embodiments, the relationship between the traveldistance of the trigger shoe 228 and the analog output of the magneticsensor 600 is non-linear, such as logarithmic or exponential. In someembodiments, the output of the magnetic sensor 600 is a voltage.However, in other embodiments, the output is a current (e.g. 4-20 mA) ora digital value.

FIG. 14A is a graph showing an example output of a digital magneticsensor, such as magnet sensor 602 and/or the digital magnetic sensor 420used by the forward-reverse selector 204. As shown in FIG. 8 , theoutput of the digital sensor varies between a digital high (“1”), and adigital low (“0”). As also shown in FIG. 14A, during a trigger pull, thedigital magnetic sensor 602 transitions to a digital high when thetrigger shoe 228 travel is approximately 2 mm. However, the digitalmagnetic sensor 602 may be configured to transition to a digital highwhen the trigger shoe 228 travel distance is less than 2 mm or greaterthan 2 mm in some embodiments. The digital sensor is further shown totransition back to a digital low during the release of the trigger shoe228. For example, the digital sensor 602 may transition back to adigital low when the trigger shoe 228 is within 0.9 mm of the fullyreleased position. However, the digital magnetic sensor 602 may also beconfigured to transition to a digital low when the trigger shoe 228 isless than 0.9 mm of the fully released position, or more than 0.9 mm ofthe fully released position.

Similarly, a transition between a digital high and a digital low mayalso be output by the digital magnetic sensor 420 used by theforward-reverse selector 204. For example, the digital magnetic sensor420 may output a digital high when the forward-reverse selector 204 isin the first locked position. In other embodiments, the digital magneticsensor 420 may output a digital high when the forward-reverse selector204 is in the second locked position. In some embodiments, the digitalmagnetic sensor 420 may transition to a digital low signal when theforward-reverse selector 204 is moved out of either the first lockedposition or the second locked position, depending on the configurationof the tool. In other embodiments, the digital magnetic sensor 420 mayonly transition between digital states when the forward-reverse selector204 is moved to one of the first or second locked positions. Forexample, the digital magnetic sensor 420 may transition to a digitalhigh when the forward-reverse selector 204 is placed in the first lockedposition, and transition to a digital low when the forward-reverseselector is placed in the second locked position, or vice versa.

FIG. 14B is a graph showing an example output of a dual output digitalmagnetic sensor, such as the digital magnetic sensor 420 used by theforward-reverse selector 204 in some embodiments. As shown in FIG. 14B,the digital magnetic sensor 420 may be configured to output a firstdigital high at a first output when the forward-reverse selector 204 isin a first position, a second digital high at a second output when theforward-reverse selector 204 is in a second position, and a digital lowon both the first output and the second output when the forward-reverseselector 204 is in a third position. For example, when theforward-reverse selector 204 is in the “forward” position, a firstdigital high 750 may be output via the first output of the digitalmagnetic sensor 420. Conversely, when the forward-reverse selector 204is in the “reverse” position, a second digital high 752 is output viathe second output of the digital magnetic sensor 420. Finally, if theforward-reverse selector 204 is in the “center” or locked position,there is a digital low at both the first output and the second output ofthe digital magnetic sensor 420. The first and second outputs may be incommunication with a controller via two or more I/O ports of thecontroller. As shown in FIG. 14B, the transitions to digital highs canbe varied based on a desired amount of rotation of the magnet 328. Forexample, a rotation of 5 degrees may be sufficient to cause a transitionfrom the digital magnetic sensor 420. However, rotations of more than 5degrees or less than 5 degrees are also contemplated.

FIG. 15 illustrates a simplified block diagram of a brushless powertool, such as power tool 100, according to some embodiments. The powertool 100 is shown to include a power source 922, a power switchingnetwork 924, a motor 926, Hall-effect sensors 928, a motor controller930, user input 932, and other components 936 (e.g., battery pack fuelgauge, work lights [LEDs], current/voltage sensors, etc.). The powersource 922 provides DC power to the various components of the power tool100 and may be a power tool battery pack that is rechargeable and uses,for instance, lithium ion cell technology. In some instances, the powersource 922 may receive AC power (e.g., 120V/60 Hz mains power) from atool plug that is coupled to a standard wall outlet, and then filter,condition, and rectify the received power to output DC power. EachHall-effect sensor 928 outputs motor feedback information, such as anindication (e.g., a pulse) when a magnet of the rotor rotates across theface of that Hall-effect sensor 928. Based on the motor feedbackinformation from the Hall-effect sensors 928, the motor controller 930can determine the position, velocity, and acceleration of the rotor.

In some embodiments, the motor controller 930 includes a memory storinginstructions and an electronic processor coupled of the memory toretrieve and execute the instructions to thereby implement thefunctionality of the controller 930 described herein. The motorcontroller 930 is also configured to receive control signals from theuser inputs 932, such as by depressing the trigger shoe 228 or actuatingthe forward-reverse selector 204. An output associated with theoperation of the user inputs 932 may be provided to the motor controller930 via the analog and digital magnetic sensors described above, such asanalog sensor 600, and digital sensors 420 and 602. Examples of thecontrol signals provided by the user inputs 932 are shown in FIGS. 13and 14 , described above. In some embodiments, the digital sensor 420may provide a control signal (e.g., a digital signal) to the controllerindicating a position of the forward-reverse selector 204, which in turninstructs the controller 930 to operate the motor 926 in either aforward or reverse direction, which may be controlled via the powerswitching network 924, as described below.

In response to the motor feedback information the control signalsreceived via the user inputs 932, the motor controller 930 transmitscontrol signals to the power switching network 924 to drive the motor926, as explained in further detail with respect to FIG. 16 . In someembodiments, the power tool 100 may be a sensorless power tool that doesnot include a Hall-effect sensor 928 or other position sensors to detectthe position of a rotor of the motor 926. Rather, the rotor position maybe detected based on the inductance of the motor 926 or the backelectromotive force (emf) generated in the motor 926. Although notexplicitly illustrated, the motor controller 930 and other components ofthe power tool 100 are electrically coupled to the power source 922 suchthat the power source 922 provides power thereto.

FIG. 16 illustrates a circuit diagram of the power switching network924. The power switching network 924 includes a number of high sidepower switching elements 940 (e.g., field effect transistors [FETs]) anda number of low side power switching elements 944 (e.g., FETs). Themotor controller 930 provides the control signals to control the highside FETs 940 and the low side FETs 944 to drive the motor based on themotor feedback information and user controls described above. Forexample, in response to detecting a pull of the trigger shoe 228 and theinput from forward-reverse selector 204, the motor controller 930provides the control signals to selectively enable and disable the FETs940 and 944 (e.g., sequentially, in pairs) resulting in power from thepower source 922 to be selectively applied to stator coils of the motor926 to cause rotation of a rotor. More particularly, to drive the motor926, the motor controller 920 enables a first high side FET 940 andfirst low side FET 944 pair (e.g., by providing a voltage at a gateterminal of the FETs) for a first period of time. In response todetermining that the rotor of the motor 926 has rotated based on a pulsefrom the Hall-effect sensors 928, the motor controller 930 disables thefirst FET pair, and enables a second high side FET 940 and a second lowside FET 944. In response to determining that the rotor of the motor 926has rotated based on pulse(s) from the Hall-effect sensors 928, themotor controller 930 disables the second FET pair, and enables a thirdhigh side FET 940 and a third low side FET 944. This sequence ofcyclically enabling pairs of high side FET 940 and low side FET 944repeats to drive the motor 926. Further, in some embodiments, thecontrol signals include pulse width modulated (PWM) signals having aduty cycle that is set in proportion to the amount of trigger pull ofthe trigger shoe 228 (as indicated by the output of the magnetic sensor600), to thereby control the speed or torque of the motor 926.

FIG. 17 is a process 1700 for controlling the output of an electricpower tool, such as power tool 100 is described, according to someembodiments. At process block 1702 an input trigger of the electricpower tool is actuated. For example, the input trigger may be thetrigger shoe 228 described above. However, other input triggers such aspushbuttons, levers, and the like may also be used. In some embodiments,the input trigger is actuated in a first linear direction (e.g., alinear pulling of the trigger shoe 228). At process block 1704, thelinear actuation of the input trigger is converted to a rotationalmovement via one or more mechanical interfaces. In some embodiments, thelinear motion of the input trigger is converted to a rotational movementusing the contactless trigger assembly 200 described above. However,other configurations for converting the linear movement of the inputtrigger to a rotational movement are also contemplated.

At process block 1706, the rotational movement is transferred to amagnet of the electric power tool, such as annular magnet 284 describedabove. For example, the magnet may be coupled to the rotating arm 288 asdescribed above. Thus, the magnet is rotated based on the actuation ofthe input trigger.

At process block 1708, an analog sensor detects variation in a magneticfield generated by the rotating magnet. In one embodiment, the sensor isa rotational Hall-effect magnetic sensor. The analog sensor may beconfigured to detect a change in a magnetic flux density component,which results from the rotation of the magnet. At process block 1710,the analog sensor converts the sensed magnetic field to an outputsignal, which may be provided to a controller, such as motor controller930, as described above. In some embodiments, the output of the analogsensor is a voltage that varies linearly with the rotation of the magnetas shown in FIG. 13 . However, in other examples, the output may be anon-linear output, such as a stepped output, a logarithmic output, etc.

At process block 1712, the controller 930, upon receiving the output ofthe analog sensor, controls an output of the electric tool based on thereceived analog sensor output. For example, the motor controller 930receives the output from the analog sensor 600 and drives the motor 926by controlling the power switching network 924 based on the output fromthe analog sensor 600, as described above. In one example, the motorcontroller 930 drives the power switching network 924 to control theoutput power to the motor 926 in a non-linear operation, as shown inmotor drive profile 1800 shown in FIG. 18 .

As shown in FIG. 18 , a first region 1802 includes lower speeds thatallow for more precise control by a user (e.g., through modulating thedepressed amount of the shoe 228). Subsequently, the second region 1804allows the tool to reach full speed earlier in the output range of thesensor (e.g. earlier in the trigger pull). As shown in FIG. 18 , thecontroller 930 may be configured to operate the output of the tool at100% power (e.g., with a pulse width modulated signal driving the powerswitching network 924 at 100% duty ratio) when the trigger pull reaches60% of full travel. This arrangement enables the output of the tool tobe at 100% power across the tolerance range of the trigger shoe 228 orother input trigger. As described above, the output of the electric toolmay be a rotational output, wherein the controller controls therotational speed of the rotational output based on the received sensoroutput. In some embodiments, the controller also receives a controlsignal from the magnetic sensor 420 associated with the forward-reverseselector 204. The motor controller 930 may then control the output ofthe power tool based on both the received output of the analog sensor600 and the control signal from the magnetic sensor 420 to control theoutput of the tool at a desired output level and also in the desireddirection.

In some embodiments, in block 1708, a digital magnetic sensor, such asdigital magnetic sensor 602 senses the variation in the magnetic fieldin addition to or instead of the analog sensor. In these embodiments,the digital magnetic sensors convert the sensed magnetic field to adigital output, such as that shown in FIG. 14 , at process block 1710.Additionally, in process block 1712, the digital output may be receivedby the controller 930 of the electric tool to initiate certainfunctions, such as instructing the controller to “wake-up” or initializein order to operate the tool. For example, if the digital magneticsensors output a digital high to the controller, the controller 930 may“wake-up” or enter a normal mode from a “sleeping” or low-power mode.For example, the controller 930 may enter a low-power mode after theelectronic tool has been inactive for a predetermined period of time(e.g. two hours). In some embodiments, as noted above, the analog sensor600 is not included and the annular magnet 284 is in communication withonly the digital magnetic sensor 602. For example, in some embodiments,where the tool 100 operates at a single speed, includes a separate speedadjusting mechanism (e.g., a jigsaw with a speed dial), or is a toolthat includes a cyclic motor operation that is enabled upon a triggerpull (e.g., a nailer or stapler), only the digital sensor 602 isincluded to detect the annular magnet 284. Thus, the control signal fromthe digital sensor 602 to the motor controller 930 acts as an enablesignal to the controller 930 and, in process step 1712, the controller930 drives the motor 926 in response to receiving the enable signal fromthe digital sensor 602.

FIGS. 19A-19C illustrate an alternative embodiment of a contactlesstrigger assembly 1900, such as contactless trigger assembly 200described above. Similar to the contactless trigger assembly 200, thecontactless trigger assembly 1900 includes a printed circuit board 1902,and an arm 1904. Similar to the contactless trigger assembly 200, thearm 1904 may be moveably coupled to a cam 1906 of a moveable plunger1908. As the moveable plunger 1908 moves along the axis A, the arm 1904is rotated in direction C. The contactless trigger assembly 1900 furtherincludes a metallic member 1910 coupled to the arm 1904 at a pivotingcam 1912, and is configured to rotate with the arm 1904. In oneembodiment, the metallic member 1910 is constructed out of a ferrousmaterial. In other embodiments, the metallic member 1910 may beconstructed out of a non-ferrous material. Example metallic materialsmay include iron, steel, aluminum, copper, and the like. An inductivecoil 1914 is coupled to the circuit board 1902, and is positionedbetween the circuit board 1902 and the arm 1904. In some embodiments, anelectrical current is provided to the inductive coil to generate amagnetic field.

As the arm 1904 rotates in a direction C, the metallic member 1910 alsorotates in the direction C. As shown in FIG. 19 , the metallic member1910 and the inductive coil 1914 are not contiguous annular shapes, butrather are curved arcs that, depending on the position of the movableplunger, overlap by a certain degree. Rotation of the metallic member1910 causes the amount of the ferrous member 1910 to vary, therebyaltering a strength of a magnetic field generated by the inductive coil1914, which is in turn detected by a sensor on the printed circuit board1902. The variance in the sensed magnetic field may be correlated to aposition of the trigger. Sensing the strength of a varying magneticfield eliminates the need for a rotational magnetic field sensor. In oneembodiment, the sensor is an analog rotational magnetic field sensor. Inother embodiments, the sensor is an inductive sensor configured to sensethe strength of the magnetic field generated by the inductive coil 1914.

As described above, the arm 1904 rotates in a direction C along with theferrous member 1910. As the arm 1904 rotates the portion of theinductive coil 1914 covered by the metallic member 1910 changes. Asshown in FIG. 19A, the trigger (not shown) is in the relaxed positioncausing the arm to be in a first position. In the first position, themetallic member 1910 is positioned such that it covers the entire lengthof the inductive coil 1914. As the arm 1904 moves due to a movement ofthe trigger into a second position as shown in FIG. 19B, the portion ofthe metallic member 1910 covering the inductive coil 1914 is reduced bya value proportional to the movement of the arm 1904. As the arm 1904reaches the maximum travel position, as shown in FIG. 19C, the portionof the metallic member 1910 covering the inductive coil 1914 is furtherreduced. By reducing the amount of the inductive coil 1914 covered bythe inductive member 1910, a magnetic field is varied, which is detectedby the sensor. The sensor is configured to provide an output to acontroller, such as motor controller 930, representative of the sensedinductive value, which may then be used to control an output of a powertool, such as described above.

FIGS. 20A-20C illustrates an alternative embodiment of the contactlesstrigger assembly 1900 as contactless trigger assembly 2000. Thecomponents and operation of the trigger assembly 200 are similar to thatof trigger assembly 1900, and it is understood that the components andoperation of the contactless trigger assembly 2000 are the same as thosein contactless trigger assembly 1900, unless noted otherwise below. Asshown in FIG. 20A, the inductive coil 1914 is positioned such that nopart of the metallic member 1910 covers the inductive coil 1914 when thetrigger is in the relaxed position (e.g. not depressed). In FIG. 20A,the trigger (not shown) is in the relaxed (e.g. not depressed) positioncausing the arm to be in a first position. In the first position, themetallic member 1910 is positioned such that it does not cover anyportion (or a minimal portion) of the inductive coil 1914. As the arm1904 moves due to a movement of the trigger into a second position asshown in FIG. 20B, the portion of the metallic member 1910 covering theinductive coil is increased by a value proportional to the movement ofthe arm 1904. As the arm 1904 reaches the maximum travel position, asshown in FIG. 20C, the portion of the metallic member 1910 covering theinductive coil 1914 is further increased. By increasing the amount ofthe inductive coil 1914 covered by the metallic member 1910, a magneticfield value is varied, which is detected by a sensor on the printedcircuit board 1902. The sensor is configured to provide an output to acontroller, such as motor controller 930, representative of the sensedmagnetic field value, which may then be used to control an output of apower tool, such as described above.

In some embodiments, the inductive coil 1914 of trigger assembly 1900and/or trigger assembly 2000 may be configured to include multiplereceiving traces or conductors that are sinusoidal in shape, but offsetby 90°, so that when the metallic member 1910 rotates, the voltageinduced in one of the traces/conductors is a sine wave and the voltagein the other trace/conductor is a cosine wave. The voltage output of thetwo traces/conductors is sensed by a sensor, such as a TX Sine Cosinesensor, and can then be provided to a controller, such as motorcontroller 930. The motor controller 930 may then determine a location(e.g. rotational angle) of the metallic member 1910 with respect to thetraces/conductors of the inductive coil 1914. In some embodiments, theangle is generated by the motor controller 930 using an arctangentfunction, a=arctan v_(sin)/v_(cos). In some embodiments, the sine-cosinesensor can achieve a resolution of approximately 0.15° for detecting theposition of the metallic member 1910, and a detection accuracy ofgreater than 98%.

Thus, embodiments described herein provide, among other things, acontactless trigger assembly for a power tool. Various features andadvantages are set forth in the following claims.

What is claimed is:
 1. A trigger assembly for a power tool comprising: amoveable plunger coupled having a first end and a second end, whereinthe first end is coupled to a magnet; a trigger shoe coupled to a secondend of the moveable plunger; and a sensor configured to sense a magneticfield of the magnet, wherein movement of the trigger shoe rotates themagnet and alters the magnetic field sensed by the sensor.
 2. Thetrigger assembly of claim 1, wherein the sensor is electricallyconnected to a controller of the power tool, the controller configuredto control an output of the power tool.
 3. The trigger assembly of claim2, wherein the sensor is configured to output a signal to the controllerbased on the sensed magnetic field.
 4. The trigger assembly of claim 3,wherein the output is a voltage indicative of a position of the triggershoe.
 5. The trigger assembly of claim 1, wherein the magnet is anannular magnet configured to rotate based on movement of the arm.
 6. Thetrigger assembly of claim 5, wherein the sensor is configured to sense achange in the magnetic field of the annular magnet in response to theannular magnet rotating.
 7. The trigger assembly of claim 1, furthercomprising: a selector disposed on a surface of a housing of the triggerassembly; a pin including a first end that is engageable with theselector and a second end that is coupled to a selector magnet; and aselector sensor configured to sense a magnetic field of the selectormagnet, wherein axial motion of the selector rotates the selector magnetand alters the magnetic field sensed by the sensor.
 8. The triggerassembly of claim 7, wherein the selector sensor is configured to sensea polarity of the selector magnet and output a digital signal to acontroller based on the sensed polarity.
 9. The trigger assembly ofclaim 8, wherein the controller is configured to execute an operatingmode selected from a plurality of operating modes of the power toolbased on the digital signal received from the selector sensor.
 10. Thetrigger assembly of claim 9, further comprising an arm having a firstside that is moveably connected to the first end of the moveable plungerand a second side that is coupled to the magnet.
 11. A method forcontrolling an output of an electric power tool, the method comprising:actuating a trigger shoe of the electric power tool in a first lineardirection; converting linear movement of the movable plunger into arotational movement of a movable arm in a first rotational direction;rotating an annular magnet coupled to the movable arm in the firstrotational direction; sensing a parameter of a magnetic field generatedby the annular magnet at a first magnetic sensor; and controlling, viathe controller, the output of the electric power tool based on thesensed parameter.
 12. The method of claim 11, wherein the output of theelectric power tool is a rotational speed.
 13. The method of claim 11,wherein the sensed parameter is a magnetic flux density vectorcomponent.
 14. The method of claim 11, wherein the first magnetic sensoris an analog rotational magnetic field sensor.
 15. The method of claim11, further comprising sensing a parameter of the magnetic fieldgenerated by the annular magnet at a second magnetic sensor, wherein thesecond magnetic sensor is a digital magnetic sensor.
 16. The method ofclaim 15, further comprising initiating a wake-up process for thecontroller based on the controller receiving an output of the secondmagnetic sensor.
 17. A trigger assembly, comprising: a trigger assemblyincluding: a housing; a selector disposed on a surface of the housing; apin including a first end that is engageable with the selector and asecond end that is coupled to a selector magnet; and a selector sensorconfigured to sense a magnetic field of the selector magnet, whereinaxial motion of the selector rotates the selector magnet and alters themagnetic field sensed by the sensor.
 18. The power tool of claim 17,wherein the trigger assembly further comprises: a trigger shoeconfigured to be actuated in a first linear direction, wherein actuationof the trigger shoe moves a movable plunger in the first lineardirection, a movable arm configured to rotate an annular magnet coupledto the movable arm in the first rotational direction, and a magneticsensor configured to sense a first parameter of a magnetic fieldgenerated by the annular magnet; and a controller configured to receivethe output voltage from the magnetic sensor and control an output of thepower tool based on the sensed parameter.
 19. The power tool of claim18, further comprising: a second magnetic sensor configured to sense asecond parameter of the annular magnet and transmit an output to thecontroller, wherein the second magnetic sensor is a digital magneticsensor, and the second parameter is a polarity of the annular magnet.20. The power tool of claim 19, wherein the controller is furtherconfigured to initiate a wake-up process for the controller based on thecontroller receiving the output of the second magnetic sensor.